Method of expanding hollow fasteners



June 10, 1947. R. c.wo1 FE METHOD OF EXPANDING HOLLOW FASTENERS Filed Oct. 9, 1943 Will/[111111Z INVENTOR.

d @L PMO ATTORNEY Patented June l0, 1947 UNITED STATES PATENT omer.

METHOD F EXPANDING HOLLOW FASTENERS Richard C. Wolfe, Middletown, R. I.

Application October 9, 1943, Serial No. 505,638

1 Claim.

I'have found that hollow fasteners can be xed to a recessed body by positioning the hollow fastener at least partly within said recessed body, activating a pressure generating charge outside of said hollow fastener and transmitting the generated pressure into the hollow fastener to expand the fastener into contact with the interior of the recessed body.

I have designed a device for producing this effect which comprises a chamber for receiving a pressure generating charge, a mechanism for activating said charge, a passage leading from said chamber for transmitting pressure generated by said activated charge and an injector means associated with the remote'end of said passage for introducing said generated and transmitted pressure into a cavity in the fastener to be expanded.

For the purpose of my description, the word activat as used herein, may include initiating an explosive, causing a chemical reaction, and releasing gas under pressure or from the solid state.

In the preferred embodiment of my invention, I use a gun having a chamber to receive a cartridge containing a gas generating material or powder, a firing pin for ring the cartridge, a gun barrel for transmitting the pressure generated by ring said cartridge and an injector nee- ,dle disposed at the end of said barrel for transmitting the pressure into the interior of a hollow fastener. The firing pin lis activated in conventional fashion by means of a trigger. In using this gun, the hollow fastener is inserted in a recess in the body to be fastened, a cartridge is inserted in the gun, the injector needle at the end of the gun is inserted inside the hollow fastener, the operator pulls the trigger on the gun, ring the cartridge so that pressure transmitted through the injector needle into the hollow fastener expands the walls thereof into close co'ntact with the walls of the recess in the body to be fastened.

My invention may be more readily understood 2 by referring to the various figures of the drawing.

In general, Figure l is a view in cross section of my gun. Figure 2 is a view of a modied injector means for the gun: Figure 3 is a view of one type of blind rivet b'efore expansion by means of my gun. Figure 4 is a view of the same rivet after expansion showing the injector and end of the gun in contact with the rivet cavity. Figure 5 is a view of a dierent type of blind rivet before expansion. Figure 6 is a view of this second type of rivet after expansion showing the gun in contact with the rivet cavity. Figures 7, 8, 9 and 10 are views of other types of blind rivets. Referring in detail to Figure l, my gun for expanding blind rivetsl and other hollow fasteners is composed ofthe grip R, the trigger S, the firing pin T, the chamber O for receiving the cartridge N, the gun barrel M with passage P for transmitting pressure, the hollow injector needle I silver soldered into brass tip J which is held tight sealed against the end of the steel gun barrel M by a threaded ferrule K, as in a pipe union except for annular ring H which is added to make tip J self-aligning.

Upon pulling trigger S, the ring pin T strikes the cartridge N conventionally primed, and loaded with smokeless powder, for instance, generating pressure in chamber O which is transmitted through passage P and through injector needle I. If this needle is inserted into a hollow fastener such as the blind rivets as shown in Figures 4 and 6, the transmitted pressure expands the walls of the hollow fastener Within the recess in the article to be fastened, such as the platesshown' in Figures 4 and 6, and beyond these plates when the fastener is the rivet as shown in these figures.

As shown in Figure 2, the injector means may be threaded to take the form of the element I' of that figure. This type of injector may be threaded into a complementary thread in the hollow fastener as shown, for instance, in Figure Referring in particular to Figure 3, the blind rivet X is provided with the annular groove Y. D is the outer diameter of the shank of the rivet and B is the diameter of the cavity in said shank. Z is that portion of the rivet shank commonly referred to as the grip, being that portion of the shank which lies within the perforation through the obiectto be riveted. The remaining end of the rivet shank extending beyond Vthe grip and accordingly beyond the object, is designated as A. Whereas the groove depth should be as shallow as possible and still perform its function, I have found that good results are obtained when this groove depth U equals approximately D minus B 6 Upon ring into this type of rivet by inserting the needle of the gun into the head end of the cavity, as shown in Figure 4, the end is blown off or aside at thc groove and the remaining portion of the shank ared outward as shown at L.

The rivet shown in Figure is the same as that in Figure 3 except for the omission of the annular groove. In this case, that portion of the shank extending beyond the grip is not blown ofl' but merely expanded like a bulb as shown in Figure 6 at W.

Figures 7, 8, 9, and 10 show various modifications of the shape of the cavity in the blind rivet and vary, from no shoulder in Figure 7, to a very denite shoulder in Figure 9, and the threaded shoulder already described in Figure 10.

Although I have described my invention in connection with the preferred embodiment thereof; namely, the gun with smokeless powder cartridge for firing blind rivets, it should be understood that various other embodiments may be employed. For instance, any suitable chemical may be employed to generate the pressure in the chamber O instead of the powder cartridge N and indeed any type of deflagrating explosive may be used in place of the smokeless powder. This includes any explosive or gas generating arrangement, such as a capsule, of solid or highly compressed gas of which solid carbon dioxide serves as an example. Likewise, the gun structure may be varied conventionally from the particular form shown so long as the essential elements are present.

The hollow fastener need not be in the form of a rivet. My invention is applicable to any hollow fastener such as a staybolt, any hollow bolt, an electrical connector, a. rail bond or any fastening element in which the fastening principle involves the use of a hollow portion to be expanded within and into contact with the object to be fastened.

This method of expanding hollow fasteners is particularly advantageous in those cases where if the explosive were in the rivet it would have to be a detonating type in that it can serve to expand such rivets without the transportation of fasteners containing detonating explosive charge and without the use of electrical ignition means, such as those required by explosive rivets containing a xed charge of detonating explosive. Instead, the expansion means constitute the cartridges loaded with deilagrating explosives which can be transported just like small arms ammunition with no particular hazard. h Y

I intend to be limited only by the following patent claim:

The method of expanding a hollow fastener having a closed end on the shank thereof and a head having a restricted passage into said hollow shank, said method comprising providing a tool having a cartridge receiving chamber, a restricted passage leading from the cartridge receiv` ing chamber and ending in a portion receivable in the restricted passage in said rivet head, placing said restricted portion of the tool in said restricted portion of the rivet head, and `exploding said cartridge while pressing said tool into said restricted opening whereby the gases formed by the explosion pass into the hollow rivet to expand the same.

RICHARD C. WOLFE.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Nardone July 16, 1940 

